The invention relates to the use of glasses containing rare earth oxides and aluminum oxide in optical waveguides.
Optical waveguides are known in the art and are used to carry optical signals along a desired path. Waveguides may be planar in shape or in the form of a fiber. These optical waveguides typically have either a thin film of material deposited upon a substrate or a core material surrounded by cladding. The material has shape and optical characteristics to form a waveguide path for the optical signals. Some types of optical waveguides may also provide amplification to the optical signals inputted into the waveguide. In general, waveguide amplifiers are pumped with an external coherent light source, that is, a laser, to cause electrons to enter higher energy bands. Once in a higher energy band, the transition to a lower energy band is such that the optical signals passing through the waveguide is amplified.
Production of small, high power density devices requires materials that dissolve large amounts of dopant in a homogeneous medium. Clustering of dopant ions restricts the use of silica-based glasses to applications where low dopant concentrations can be used, that is, relatively large devices. The ongoing desire for compact devices for optical signal processing, optical signal amplification, and high power density laser applications has prompted the development of new optical waveguide materials that can support larger concentrations of dopants than the glasses used currently.